A hierarchy-invariant Virtual Maintenance Model (hiVMM) is proposed in this paper, in which the structure of the assembly tree of the equipment is kept invariably during the whole process of assembly and disassembly manipulation. A deterministic finite automatic machine of assembly and disassembly process for a component has been defined. The hierarchical model not only improves the efficiency of assembly and disassembly operations but also maintains the hierarchical structure of the equipment, avoiding making parts and components of the equipment in a mess when they are organized and manipulated in a flat space. Then related components and parts and their hierarchical relationship node prototype are defined using VRML. In the end, a hiVMM of a hook is constructed and implemented based on VRML to prove its high manipulation efficiency.